1. Field of the Invention
This invention generally relates to magnetic disk drives, which drive spindle motors to rotate magnetic disks so that magnetic heads read and write information on the magnetic disks. Particularly, this invention relates to improvements in mechanical structures of the magnetic disk drives whose thickness is reduced and which are improved in impact resistance and heat radiation.
This application is based on Patent Application No. Hei 10-328658 filed in Japan, the content of which is incorporated herein by reference.
2. Description of the Related Art
First, a description will be given with respect to impact resistance of the conventional magnetic disk drives.
In general, the magnetic disk drives are very weak against impact being applied from the external. So, there is a possibility that the magnetic disk drives are remarkably reduced in life when human operators (or users) drop the magnetic disk drives on desks so that small impact of 100 G is applied to the magnetic disk drives. For this reason, in an event in which the user drops the magnetic disk drive from the desk to the floor so that large impact of 1000 G or more is applied to the magnetic disk drive, the magnetic disk drive may be fatally damaged.
There are two reasons why the magnetic disk drives have weakness against the impact, as follows:
A first reason is occurrence of jumping in which the magnetic head jumps due to impact being applied to the magnetic disk drive. In that case, the magnetic head hits a magnetic recording medium, so that a medium surface and the head are damaged. It is known that in general, the head is subjected to jumping due to impact of 100 G or so.
To avoid occurrence of the jumping of the head, the conventional technology employs a method to refuge the head outside of the medium at a stop mode of the magnetic disk drive. Even in such a method, however, it is unavoidable that a suspension portion for supporting the head is deformed and damaged due to impact of 1000 G or more.
A second reason is damageability in which a bearing of a spindle motor for rotating the medium is easily damaged.
In case of a ball bearing, for example, load corresponding to a product of xe2x80x9c(impact acceleration)xc3x97(mass of body of revolution)xe2x80x9d concentrates at the bearing. This causes impressions to be formed on a ball and its sliding surface.
To avoid the above problems, engineers discuss using pressure bearings as the bearings. The pressure bearing receives impact by xe2x80x9cline contactxe2x80x9d, which approximates to xe2x80x9csurface contactxe2x80x9d. As compared with the ball bearing, the pressure bearing is improved in impact resistance. Until now, however, the pressure bearing does not have sufficient reliability to accomplish required functions of the bearing. So, the present technology does not proceed to adoption of the pressure bearing to the magnetic disk drive. Even if the magnetic disk drive uses the pressure bearing, the pressure bearing merely provides impact resistance of several-hundreds G class. So, it cannot be said that the magnetic disk drive using the pressure bearing sufficiently overcomes large impact which exceeds 1000 G.
To cope with the aforementioned problems, engineers and scientists propose a variety of techniques with regard to shock absorber mechanisms of the magnetic disk drives.
For example, Japanese Patent Application, First Publication No. Hei 4-368690 discloses a magnetic disk drive, which is equipped with shock absorbers made of chloroprene rubber at four corners of a housing.
Japanese Patent No. 2594760 (corresponding to Japanese Patent Application, First Publication No. Hei 8-36873) discloses a magnetic disk drive equipped with shock absorbers (or bumpers) made of elastic material, which are installed in recesses formed at outer edge portions of a base of the magnetic disk drive.
In addition, Japanese Patent Application, First Publication No. Hei 6-176555 discloses a magnetic disk drive equipped with a shockabsorber added structure. Herein, shock absorbers are arranged at four corners of a frame as well as some portions in proximity to both ends of a connector receiving portion. Those shock absorbers damps impacts being applied to the magnetic disk drive. So, it is possible to prevent internal mechanical parts and members of the magnetic disk drive from being damaged.
Next, a description will be given with respect to measures against the heat that the magnetic disk drives generate. In general, the magnetic disk drive is constructed by a disk enclosure for installing mechanical parts such as a spindle motor and an actuator as well as a package for mounting electronic components used for control.
Among the aforementioned parts and components, main heating sources are the spindle motor, a coil portion of the actuator and IC parts such as control channels.
It is well known that if the magnetic disk drive operates for a long time, a surface temperature increases by 30 degrees or more. If a using environment is severe in temperature which exceeds 50 degrees (Celsius), there is a possibility in which temperature of the magnetic disk drive exceeds 80 degrees (Celsius). In such an high-temperature event, the magnetic disk drive is placed in an uncontrollable state, so it malfunctions.
To cope with the aforementioned problem, the conventional technology uses a fan which is arranged in a housing (or case) installing the magnetic disk drive. Using such a fan, the magnetic disk drive is cooled down to avoid temperature increase.
Japanese Patent Application, First Publication No. Hei 9-115279 discloses a magnetic disk drive equipped with heat conductive members as heat radiators. Herein, heat conductive members are tightly adhered to the package, disk enclosure and housing. Specifically, heat conductive sheets are inserted into a gap between the disk enclosure and electronic components on the package as well as a gap between the disk enclosure and a wall of a housing for installing the disk enclosure. Those sheets radiates heat of the package and heat of the disk enclosure due to thermal conductivity.
Next, a description will be given with respect to a conventional installation method for installing the package mounting electronic components in the disk enclosure.
The conventional 3.5-inch (or 2.5-inch) magnetic disk drives using 3.5 inch (or 2.5 inch) disks employ a specific structure for installation. For example, the magnetic disk drive disclosed by Japanese Patent Application, First Publication No. Hei 9-115279 employs a structure in which the package is attached to a back of the disk enclosure.
The aforementioned structure is subjected to standardization, which determines positions for screwing the disk enclosure on the housing and a position for arranging a connector on the package. Thus, it is possible to install the magnetic disk drives in spaces, which are prepared in advance in personal computers and servers, with compatibility.
In general, the packages are uncovered. So, users are able to directly touch important electronic components of the packages.
As described above, the 3.5-inch (or 2.5-inch) magnetic disk drives are standardized in structures for installation in the housings (or main bodies). So, the magnetic disk drives are tightly screwed on the housings.
In the case of the personal computers, the magnetic disk drives are fixed to sheet metals of the housings by screws, so they are installed in the housings. In the case of the servers, the magnetic disk drives are fixed to racks exclusively used for installation of the magnetic disk drives by screws, then, the racks are inserted into the servers.
The packages normally use SCSI connectors or IDE connectors (where xe2x80x9cSCSIxe2x80x9d is an abbreviation for xe2x80x9cSmall Computer Systems Interfacexe2x80x9d, while xe2x80x9cIDExe2x80x9d is an abbreviation for xe2x80x9cIntegrated Device Electronicsxe2x80x9d). Those connectors are not designed in consideration of repetition of insertion and extraction which are repeated many times. So, they are connected to the hard disk drives with very strong connecting forces.
The aforementioned conventional techniques regarding the hard disk drives suffer from problems as follows:
A first problem is incapability to obtain a sufficient damping effect against impact. That is, the magnetic disk drive disclosed by Japanese Patent Application, First Publication No. Hei 6-176555 use xe2x80x9csmallxe2x80x9d shock absorbers, which are incapable of sufficiently absorbing (or eliminating) large impact being applied thereto.
To secure sufficient largeness of the shock absorbers, the xe2x80x9clargexe2x80x9d shock absorbers suppress spaces used for mechanical parts in the disk enclosure. For example, a magnetic circuit must be reduced in size in proximity to a corner used for installation of the actuator in the disk enclosure. This deteriorates seek characteristic of the magnetic disk drive.
Another corner aside the medium is a space for installation of an air filter in the disk enclosure. If the shock absorbers are enlarged, it becomes impossible to install the air filter in that corner of the disk enclosure.
A second problem is occurrence of noise and vibration in the magnetic disk drive equipped with a fan. Using the fan, it is possible to cool down the magnetic disk drive. However, the fan inevitably causes noise and vibration to occur.
Normally, the personal computers and severs placed in offices do not have difficulty due to the noise. However, the personal computers for home use may sometimes suffer from the difficulty due to the noise. Recently, the users frequently connect the magnetic disk drives to audio/visual devices. In that case, the noise may be a fatal drawback.
The vibration causes low-frequency noise, which forms an external disturbance for positioning of the head of the magnetic disk drive. Recently, the magnetic disks are advanced to have high densities in which tracks are formed with small pitches. This demands high positioning performance for the magnetic disk drives. For this reason, if the disturbance for normally causing vibration exists in proximity to the magnetic disk drive, it causes a great difficulty in improvement of performance of the magnetic disk drive.
Further, the magnetic disk drive disclosed by Japanese Patent Application, First Publication No. Hei 9-115279 uses the sheets exclusive used for thermal conductivity, which raise the total cost in manufacture.
A third problem is difficulty in reduction of thickness of the magnetic disk drive as a whole. That is, it is difficult to reduce the thickness of the magnetic disk drive, in which the disk enclosure and the package mounting the electronic components are arranged in a laminated-structure manner.
Due to the laminated structure, it is difficult to radiate heat from the disk enclosure and package respectively. Because, the disk enclosure and package are arranged such that heat-radiating surfaces thereof are opposite to each other, which causes heat accumulation to easily occur in a space between the heat-radiation surfaces. Herein, heat-radiation area is reduced because the heat-radiating surfaces are arranged opposite to face with each other.
In addition, the laminated structure are disadvantageous in that the electronic components are easily damaged. Further, the magnetic disk drive employing the laminated structure is not a good item for merchandise because the user may feel it unattractive while the user may have a difficulty to handle it.
Mainly because, the package mounting the electronic components are exposed. So, electrostatic destruction is easily caused to occur when the user directly touches the electronic components.
Because of exposure of the electronic components, the magnetic disk drive is not good in appearance as merchandise. In addition, the user feels difficulty to handle it with his or her hand(s). If the 2.5-inch (or 3.5-inch) magnetic disk drives storing large capacity of files are advanced to have portability in the future, the laminated structure cannot provide the magnetic disk drives with attraction to the consumers in merchandise.
A fourth problem is difficulty in installation and extraction of the magnetic disk drives. That is, it is not easy for the users to install or extract the magnetic disk drives in main bodies of the personal computers and servers.
Because, the magnetic disk drives are fixed to the main bodies of the personal computers by use of screws, while the connectors normally used for connections between the magnetic disk drives and personal computers have great strength of connection.
Conventionally, once the magnetic disk drive is installed in the main body, it is rarely extracted from the main body only when failure occurs on the personal computer or only when the user installs some board or unit more than the boards and units being installed in the personal computer in advance. So, the standardization is made with respect to the conventional magnetic disk drives in consideration of the aforementioned conditions.
In the future, the magnetic disk drives tend to be used as storage of video files or else. In that case, it is possible to propose new uses for the magnetic disk drives, in which magnetic disk drives of large capacities are used as xe2x80x9cportablexe2x80x9d devices. By the way, the magnetic disk drives of the card type (e.g., PCMCIA cards, TYPE 2, where xe2x80x9cPCMCIAxe2x80x9d is an abbreviation for xe2x80x9cPersonal Computer Memory Card International Associationxe2x80x9d) are known as magnetic disk drives of the portable type. However, those magnetic disk drives have problems due to lack of capacities. Therefore, it is demanded to provide brand-new magnetic disk drives of the 2.5-inch class, 3.5-inch class or larger classes, which are designed to be of the portable type and which can be easily installed or extracted in the personal computers and the like.
It is an object of the invention to provide a magnetic disk drive having high impact resistance as well as high thermal radiation which eliminates necessity of installation of thermal conductive members and fan.
It is another object of the invention to provide a xe2x80x9cportablexe2x80x9d magnetic disk drive of large capacity having a reduced thickness and a well considered structure, by which electronic components are hard to be damaged.
It is a further object of the invention to provide a magnetic disk drive having an attractive look and an easy-to-handle structure as merchandise, which can be easily installed or extracted in a personal computer or else.
The magnetic disk drive is basically constructed by at least one magnetic disk, a spindle motor, an actuator containing a magnetic head, a flexible printed-circuit board and a package. Herein, mechanical parts are basically installed in a disk enclosure, while electronic parts are mounted on the package.
A magnetic disk drive of this invention is characterized by that a base is extended in both sides of the disk enclosure to provide multipurpose spaces, which are equipped with a shockabsorber mechanism for improvement of impact resistance and/or a heat-radiation mechanism for improvement of heat radiation. The package is stored in the multipurpose space, which is covered with a back cover being attached to the base of the magnetic disk drive. Thus, it is possible to reduce an overall thickness of the magnetic disk drive; it is possible to improve portability of the magnetic disk drive; and it is possible to prevent the electronic components from being damaged or subjected to electrostatic destruction.
In addition, side rails are formed on exterior walls of the multipurpose spaces of the base, by which the magnetic disk drive is guided when being installed in a main device such as a personal computer and a server. Thus, it is possible to ease installation and extraction of the magnetic disk drive in the main device. Further, a rubber connector is provided for the package and is connected with a terminal of the main device with ease.
Incidentally, the main device is equipped with an installation mechanism, which assists installation (and extraction) of the magnetic disk drive. Herein, the installation mechanism is constructed by a pair of guides, a pair of anti-insertion pins, a pair of eject springs and a pair of clampers. Herein, the guides are used to guide the side rails of the magnetic disk drive being inserted into the main device. The dampers are manually revolved to lock or unlock motion of the magnetic disk drive in the main device.